Just 45 minutes a week of moderate to vigorous exercise may help improve or maintain a high level of function for people with osteoarthritis (OA), according to study published online recently in Arthritis Care & Research.
Current guidelines from the Department of Health and Human Services for adults recommend a minimum of 150 minutes per week of physical activity, which has been shown to help prevent heart disease, depression, osteoporosis, diabetes and colon and breast cancer as well as to prolong life. Fewer than half of Americans meet these standards, however, and many people with arthritis are even less physically active than people in the general population, according to senior study author Rowland Chang, MD, a professor of rheumatology and epidemiology at Northwestern University Feinberg School of Medicine, in Chicago.
“The federal guidelines suggest we should be telling patients to try to achieve 150 minutes of moderate-intensity physical activity each week in at least 10-minute segments. That’s about the equivalent of walking to a meeting you’re late for; at the end of 10 minutes, you’re slightly sweaty and a little out of breath,” says Dr. Chang. “But at best a quarter of people with arthritis aren’t able to get to that threshold. They think their knees can’t tolerate that amount and intensity of activity.”
So Dr. Chang and his colleagues, who have extensively studied the link between physical activity and physical function among people with OA, set out to discover if a less intimidating activity goal might encourage OA patients to move more.
To do this, they followed a subgroup of more than 1,600 patients enrolled in the Osteoarthritis Initiative, a multi-center study looking at risk factors for OA. Participants ranged from 49 to 83 years old and most (93 percent) had knee problems. Sixty percent had hip problems and more than half of participants had both. A smaller percentage reported arthritis symptoms in their feet or ankles.
At the beginning of the study, participants were placed in one of five groups according to their level of physical function, from highest to lowest. Their function was measured by patient self-reporting (based on a short survey) and/or by gait speed (how fast they could walk). The study authors chose to measure gait speed because it’s a good indicator of a person’s overall health and quality of life.
Participants were then fitted with activity-tracking devices called accelerometers to measure the amount and intensity of physical activity they engaged in over a week. When they were re-evaluated two years later, more than one-third had improved enough in gait speed and self-reported physical function to move up to a higher-function group. Improvement – or maintenance, if they were already in the highest functioning group – was most likely for those who got at least 45 minutes a week of moderate to vigorous activity, mainly walking, even though that falls far short of government recommendations.
“The federal guidelines are based on studies that looked at cardiovascular outcomes and mortality. Our group wanted to look at function and disability – at the quality, not the quantity of life – so we used a functional outcome as our endpoint,” explains Dr. Chang who is also the board chair of the Arthritis Foundation. “We were interested in finding [something] that could give us guidance as to what we should be telling patients if they want to improve or maintain their function.”
The researchers expected to find that people would improve functionally with less exercise and possibly less intensity than called for in the federal guidelines. But lead study author Dorothy Dunlop, PhD, a professor of rheumatology and preventive medicine at Northwestern University, stresses that the more ambitious government recommendations confer greater health benefits and all adults, even older adults and those with arthritis, should aim for them; 45 minutes is just a good starting point.
Dr. Chang says patients who have trouble exercising because of pain or balance issues may want to consider trying, for example, joint injections, physical therapy to improve strength or, in some cases, wearing orthotics (shoe inserts).
“There is no question that people who become more physically active feel better and hurt less. But I really feel it’s important for them to self-discover this, so they own it and incorporate it into their daily life,” he says.
Laith Jazrawi, MD, an orthopedic surgeon and chief of sports medicine at NYU Langone Medical Center in New York, says the Northwestern study “isn’t earth-shattering,” but adds more to the body of evidence about the importance of exercise for people with arthritis.
“In orthopedics, we have a concept that ‘motion is lotion,’” he explains. “In a way, it seems counterintuitive that walking and being active would improve joint function and pain, but we know from other studies that compared to [people] who are sedentary, patients who are more active have greater cartilage volume, and more cartilage means better knee function. That’s why we want to get people moving right away after knee replacement surgery – bending the knee gets the cartilage to form quicker. And as this study shows, even at 45 minutes a week, people are starting to get some benefits in overall joint motion and function.”
The goal, he says, is to find an exercise plan for each patient that isn’t high impact. Instead of jogging or running, he recommends a combination of brisk walking, cycling, swimming and weight training.
“Cross-training is a very effective approach for people with arthritis,” he says. I don’t operate on the majority of patients. [Instead], we tell them, ‘We’re going to work with you and keep you functional.’ Most patients want to be active, and I’m here to help them do that.”
Author: Linda Rath for the Arthritis Foundation